It's very exciting to think I could see asteroid mining in my life - but I have to wonder if it's solving the most crucial problem. Is earth really that strapped for metal? It seems to me that the energy used to return mass from the asteroid will quickly become far more valuable than whatever they bring back. Unless they are returning mostly stuff that is really rare on earth.
To me, it's all about the composition of the asteroid that you choose to mine.
In these early days, I think we'll probably be more focused on targets of opportunity, but once the technology base exists to be picky, if you could locate a body full of precious metals, say gold and platinum, it could easily dwarf the earthbound supply.
I think the most interesting opportunities lie not with traditional methods of exploiting these materials, but with the methods we will discover once previously rare materials become abundant and cheap.
Of course, devaluing gold to the point of aluminum is going to cause political upheaval and that will have to be dealt with, and while this conjures images of chaos and serious trouble, it doesn't seem like all that big of a deal compared to what will happen when a private entity starts talking about bringing a dinosaur-killer-sized body near the earth.
One possible advantage to the energy situation is that if you have a space elevator or similar structure, bringing lumps of asteroid down it counterbalances bringing other things back up.
